From: tip-bot for Pan Xinhui <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: torvalds@linux-foundation.org, xinhui.pan@linux.vnet.ibm.com,
tglx@linutronix.de, mingo@kernel.org, hpa@zytor.com,
boqun.feng@gmail.com, linux-kernel@vger.kernel.org,
peterz@infradead.org
Subject: [tip:locking/core] locking/pv-qspinlock: Use cmpxchg_release() in __pv_queued_spin_unlock()
Date: Thu, 22 Sep 2016 07:02:46 -0700 [thread overview]
Message-ID: <tip-b193049375b04df3ada8c3347b7083db95918bc3@git.kernel.org> (raw)
In-Reply-To: <1474277037-15200-2-git-send-email-xinhui.pan@linux.vnet.ibm.com>
Commit-ID: b193049375b04df3ada8c3347b7083db95918bc3
Gitweb: http://git.kernel.org/tip/b193049375b04df3ada8c3347b7083db95918bc3
Author: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
AuthorDate: Mon, 19 Sep 2016 05:23:52 -0400
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 22 Sep 2016 15:25:51 +0200
locking/pv-qspinlock: Use cmpxchg_release() in __pv_queued_spin_unlock()
cmpxchg_release() is more lighweight than cmpxchg() on some archs(e.g.
PPC), moreover, in __pv_queued_spin_unlock() we only needs a RELEASE in
the fast path(pairing with *_try_lock() or *_lock()). And the slow path
has smp_store_release too. So it's safe to use cmpxchg_release here.
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: virtualization@lists.linux-foundation.org
Cc: waiman.long@hpe.com
Link: http://lkml.kernel.org/r/1474277037-15200-2-git-send-email-xinhui.pan@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/locking/qspinlock_paravirt.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index 3acf16d..e3b5520 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -540,7 +540,7 @@ __visible void __pv_queued_spin_unlock(struct qspinlock *lock)
* unhash. Otherwise it would be possible to have multiple @lock
* entries, which would be BAD.
*/
- locked = cmpxchg(&l->locked, _Q_LOCKED_VAL, 0);
+ locked = cmpxchg_release(&l->locked, _Q_LOCKED_VAL, 0);
if (likely(locked == _Q_LOCKED_VAL))
return;
next prev parent reply other threads:[~2016-09-22 14:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-19 9:23 [PATCH v7 0/6] Implement qspinlock/pv-qspinlock on ppc Pan Xinhui
2016-09-19 9:23 ` [PATCH v7 1/6] pv-qspinlock: use cmpxchg_release in __pv_queued_spin_unlock Pan Xinhui
2016-09-22 14:02 ` tip-bot for Pan Xinhui [this message]
2016-09-19 9:23 ` [PATCH v7 2/6] powerpc/qspinlock: powerpc support qspinlock Pan Xinhui
2016-09-19 9:23 ` [PATCH v7 3/6] powerpc: pseries/Kconfig: Add qspinlock build config Pan Xinhui
2016-09-19 8:40 ` kbuild test robot
2016-09-19 9:23 ` [PATCH v7 4/6] powerpc: lib/locks.c: Add cpu yield/wake helper function Pan Xinhui
2016-09-22 15:17 ` Boqun Feng
2016-09-19 9:23 ` [PATCH v7 5/6] powerpc/pv-qspinlock: powerpc support pv-qspinlock Pan Xinhui
2016-09-19 9:23 ` [PATCH v7 6/6] powerpc: pSeries: Add pv-qspinlock build config/make Pan Xinhui
2016-09-19 8:58 ` kbuild test robot
2016-09-22 5:54 ` xinhui
2016-09-22 10:31 ` Michael Ellerman
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